bluetooth: hci: Fix UAF from MGMT_OP_REMOVE_ADV_MONITOR during closure

When hci_dev is closing down, mgmt_power_off will free parts of the device. The freed memory can then be accessed when processing pending MGMT_OP_REMOVE_ADV_MONITOR cmds. Since submitting the command is allowed when it is powered off (as in previous discussions linked below), fix this by returning MGMT_STATUS_BUSY to pending MGMT_OP_REMOVE_ADV_MONITOR operations submitted as hci_dev_close_sync is running. Avoid processing pending cmds since doing so will lead to reacquiring the same lock. Add a sanity check within mgmt_remove_adv_monitor to ensure the cmd is still valid and exit early if not.

BUG: KASAN: slab-use-after-free in mgmt_remove_adv_monitor_sync+0x3a/0xd0
net/bluetooth/mgmt.c:5543
Read of size 8 at addr ffff88814128f898 by task kworker/u9:4/5961

 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 mgmt_remove_adv_monitor_sync+0x3a/0xd0 net/bluetooth/mgmt.c:5543
 hci_cmd_sync_work+0x22b/0x400 net/bluetooth/hci_sync.c:332
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa63/0x1850 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>

Freed by task 16022:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:582
 poison_slab_object mm/kasan/common.c:247 [inline]
 __kasan_slab_free+0x59/0x70 mm/kasan/common.c:264
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2338 [inline]
 slab_free mm/slub.c:4598 [inline]
 kfree+0x196/0x420 mm/slub.c:4746
 mgmt_pending_foreach+0xd1/0x130 net/bluetooth/mgmt_util.c:259
 __mgmt_power_off+0x183/0x430 net/bluetooth/mgmt.c:9550
 hci_dev_close_sync+0x6c4/0x11c0 net/bluetooth/hci_sync.c:5208
 hci_dev_do_close net/bluetooth/hci_core.c:483 [inline]
 hci_dev_close+0x112/0x210 net/bluetooth/hci_core.c:508
 sock_do_ioctl+0x158/0x460 net/socket.c:1209
 sock_ioctl+0x626/0x8e0 net/socket.c:1328
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xf5/0x170 fs/ioctl.c:892
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

---
 net/bluetooth/hci_sync.c |  5 +++--
 net/bluetooth/mgmt.c     | 18 ++++++++++++++++--
 2 files changed, 19 insertions(+), 4 deletions(-)

index c86f4e42e..aa5aa3fed 100644
@@ -5197,6 +5197,9 @@ int hci_dev_close_sync(struct hci_dev *hdev)
 	 */
 	drain_workqueue(hdev->workqueue);
 
+	/* flush cmd  work */
+	flush_work(&hdev->cmd_work);
+
 	hci_dev_lock(hdev);
 
 	hci_discovery_set_state(hdev, DISCOVERY_STOPPED);

@@ -5234,8 +5237,6 @@ int hci_dev_close_sync(struct hci_dev *hdev)
 		clear_bit(HCI_INIT, &hdev->flags);
 	}
 
-	/* flush cmd  work */
-	flush_work(&hdev->cmd_work);
 
 	/* Drop queues */
 	skb_queue_purge(&hdev->rx_q);

index b31192d47..6d2e5253b 100644
@@ -5519,9 +5519,16 @@ static void mgmt_remove_adv_monitor_complete(struct hci_dev *hdev,
 {
 	struct mgmt_rp_remove_adv_monitor rp;
 	struct mgmt_pending_cmd *cmd = data;
-	struct mgmt_cp_remove_adv_monitor *cp = cmd->param;
+	struct mgmt_cp_remove_adv_monitor *cp;
+
+	// if executing while device is closing down, status could
+	// be invalid as pending cmd could be removed by __mgmt_power_off
+	// so exit early.
+	if (status == -EINVAL || cmd != pending_find(MGMT_OP_REMOVE_ADV_MONITOR, hdev))
+		return;
 
 	hci_dev_lock(hdev);
+	cp = cmd->param;
 
 	rp.monitor_handle = cp->monitor_handle;
 

@@ -5540,6 +5547,10 @@ static void mgmt_remove_adv_monitor_complete(struct hci_dev *hdev,
 static int mgmt_remove_adv_monitor_sync(struct hci_dev *hdev, void *data)
 {
 	struct mgmt_pending_cmd *cmd = data;
+
+	if (cmd != pending_find(MGMT_OP_REMOVE_ADV_MONITOR, hdev))
+		return -EINVAL;
+
 	struct mgmt_cp_remove_adv_monitor *cp = cmd->param;
 	u16 handle = __le16_to_cpu(cp->monitor_handle);
 

@@ -9544,8 +9555,11 @@ void __mgmt_power_off(struct hci_dev *hdev)
 	 */
 	if (hci_dev_test_flag(hdev, HCI_UNREGISTER))
 		match.mgmt_status = MGMT_STATUS_INVALID_INDEX;
-	else
+	else {
+		match.mgmt_status = MGMT_STATUS_BUSY;
+		mgmt_pending_foreach(MGMT_OP_REMOVE_ADV_MONITOR, hdev, cmd_status_rsp, &match);
 		match.mgmt_status = MGMT_STATUS_NOT_POWERED;
+	}
 
 	mgmt_pending_foreach(0, hdev, cmd_complete_rsp, &match);
 

2.46.0

This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list. This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=916223

---Test result---

Test Summary:

CheckPatch                    PENDING   0.34 seconds
GitLint                       PENDING   0.37 seconds
SubjectPrefix                 FAIL      0.34 seconds
BuildKernel                   PASS      25.31 seconds
CheckAllWarning               PASS      27.56 seconds
CheckSparse                   PASS      30.91 seconds
BuildKernel32                 PASS      25.33 seconds
TestRunnerSetup               PASS      445.38 seconds
TestRunner_l2cap-tester       PASS      20.43 seconds
TestRunner_iso-tester         FAIL      33.58 seconds
TestRunner_bnep-tester        PASS      4.73 seconds
TestRunner_mgmt-tester        FAIL      119.64 seconds
TestRunner_rfcomm-tester      PASS      7.57 seconds
TestRunner_sco-tester         PASS      9.19 seconds
TestRunner_ioctl-tester       PASS      8.05 seconds
TestRunner_mesh-tester        PASS      5.85 seconds
TestRunner_smp-tester         PASS      6.93 seconds
TestRunner_userchan-tester    PASS      4.92 seconds
IncrementalBuild              PENDING   0.99 seconds

Details
##############################
Test: CheckPatch - PENDING
Desc: Run checkpatch.pl script
Output:

##############################
Test: GitLint - PENDING
Desc: Run gitlint
Output:

##############################
Test: SubjectPrefix - FAIL
Desc: Check subject contains "Bluetooth" prefix Output:
"Bluetooth: " prefix is not specified in the subject
##############################
Test: TestRunner_iso-tester - FAIL
Desc: Run iso-tester with test-runner
Output:
WARNING: possible circular locking dependency detected
Total: 125, Passed: 121 (96.8%), Failed: 0, Not Run: 4
##############################
Test: TestRunner_mgmt-tester - FAIL
Desc: Run mgmt-tester with test-runner Output:
Total: 492, Passed: 487 (99.0%), Failed: 1, Not Run: 4

Failed Test Cases
LL Privacy - Start Discovery 2 (Disable RL) Failed 0.179 seconds
##############################
Test: IncrementalBuild - PENDING
Desc: Incremental build with the patches in the series Output:

---
Regards,
Linux Bluetooth